Justice Secretary Chris Grayling has defended the decision for David Cameron and Boris Johnson to go ahead with a tennis match secured by a controversial £160,000 donation to the Conservatives, insisting big Tory backers do not "buy" party policy.
Mr Grayling said that the party was perfectly entitled to accept the donation made by the wife of a Russian oligarch as she was a British citizen.
The Justice Secretary was spearheading a fresh Conservative attack on Labour's links with the unions - claiming that Ed Miliband would be more dependent on union funding than any Labour leader before him.
But, appearing on the BBC Radio 4 Today programme, he came under pressure over his party's decision to accept the donation from the wife Vladimir Chernukhin, who served as deputy finance minister in Vladimir Putin's first administration.
"Well, the tennis match is going ahead because it's a donation from a British woman, a British citizen who is perfectly entitled to make a donation," he said.
"A wide range of people contribute money to the Conservative Party. They have to be legal British donors and in that particular case this was a British woman who happens to be married to a former Russian minister who was sacked by Vladimir Putin 10 years ago."
He added: "W hen you contribute money to the Conservative Party, you don't buy policy decisions. Those people who contribute money to the Conservative Party... do it because they believe a Conservative government is best for Britain."
Mr Johnson also said it was right that the match should go ahead - although he said that as yet no date had been set.
"It's very important that we don't, as Londoners, start lashing out against all Russians everywhere," he said.
"It seems the people in question are not associated with the Putin regime, quite the reverse, they seem to be hostile to it."
In a speech in London, Mr Grayling accused Labour of being involved in "shoddy backroom deals" to devise policy that meets the demands of major donor Unite and its boss Len McCluskey.
" Len McCluskey and his colleagues made Ed Miliband leader, and they now want to make him prime minister," he said.
"Ed Miliband will be more dependent on union money in 2015 than any Labour leader before him. All that money will come with a price. No one seriously believes the union bosses are providing all that cash for nothing."
For Labour, shadow cabinet office minister Michael Dugher dismissed his comments as "absolute garbage" from the "Tory lie machine".
"Chris Grayling seems to have confused the Labour Party, who never have and never will link donations to policy, with the Conservative Party who have rewarded the few City fat cats - who give them millions of pounds - with tax cuts for millionaires and hedge funds," he said.
Mr McCluskey said: "Even by their own standards of rank hypocrisy, the Tories are today setting a new benchmark for double standards. They denounce trade unions while they fill their pockets with Moscow gold supplied by an ever-increasing number of donations for dodgy Russian oligarchs."